| How is incidence and epidemiology of thyroid cancer? | Most common malignant endocrine tumor, <1% of all malignancies, incidence varies one country to another (USA 16/100,000 , eu 15/100,000
Females > Males, increasing globally, mostly due to papillary thyroid cancer
MR low (0.5-0.7/100,000 in a year) |
| What are risk factors for thyroid cancer? | Papillary cancer (radiation exposure, inherited condition (FAP), family hx (5% runs in families), gender (3x more in women but in men rapid and spreads quickly))
Follicular thyroid cancer (low-iodine diet, familial conditions (inherited, Werner's / Cowden's))
Medullary thyroid cancer MTC (family hx 25% inheritied RET gene)
Nodules common but cancer is rare (5% of all nodules) |
| What are types of thyroid cancer? | Differentiated thyroid carcinoma (DTC), follicular epithelial cells includes Papillary thyroid carcinoma (PTC - 80%) and Follicular Thyroid carcinoma (FTC-20%)
Medullary thyroid carcinoma (MTC) calcitonin producing parafollicular cells 5%
Anaplastic thyroic carcinoma (ATC) 1-3% undifferentiated. |
| What is NFITP (non-invasive follicular thyroid neoplasm)? | Encapsulated non-invasive follicular PTC are called NFITP, they have low-grade behavior, 20% of cases in europe, no risk of cancer death and recurrence <1%, dx requires pathological exam seeing follicular pattern nodule exclude capsular invasion and papillary formation.
Correct identification reduces unnecessary use of surgery and radioactive iodine (Not a cancer) |
| What is papillary thyroid carcinoma (PTC)? | Most common thyroid malignancy (80%), associated w/previous exposure to ionizing radiation, presents in any age (common 20-40), male/female 1/3, presentation (asymptomatic nodule, first manifestation may be enlargement of cervical lymph node (first metastasis), distant metastasis to lungs and bones (5-10%) |
| What is the tx of papillary thyroid carcinoma? | Surgery (lobectomy (low risk cases), total thyroidectomy, lymph node dissection in case sus of lymph node metastasis.)
Radioactive iodine ablation if indicated
Levothyroxine therapy
Very good prognosis. |
| What is follicular thyroid carcinoma? | 2nd most common thyroid malignancy (20%), female:male 3:1, presents at advanced age (40-50), presentation is slow enlargement painless thyroid mass, low propensity for invading lymphatics, vascular invasion common w/metastasis to bone, lungs and liver (Distant sites), higher rate of metastasis (20%) |
| What is tx of follicular thyroid carcinoma? | Similar to papillary (total or near total thyroidectomy, well differentiated metastases take up radioactive iodine
Prognosis very good. |
| What are prognostic factors in DTCs? | Important to predict death and recurrence.
Age <55 and >10, male gender, histology tall columnar and degree of differentiation and vascular invasion, tumor extent size, extrathyroidal invasion, lymph node metastasis and distant metastasis. |
| What are ways of staging and stratification of risk of thyroid cancer? | Predict mortality: TNM, MACIS (metastasis, age of presentation, completeness of surgical resection, invasion, size)
Predict recurrence (ATA risk stratification) |
| Describe TNM classification of thyroid cancer. | T (Tx (cannot assess) T0 (no tumor), T1 (tumor 2cm or less limited to thyroid), T1a (tumor <1cm), T1b (tumor between 1 and 2 cm), T2 (Tumor between 2-4 cm limited to thyrodi), T3a (Tumor >4cm limited ) T3b (any size but w/extrathyroid strap muscle invasion), T4a (beyond capsule invades larynx/trachea...) T4b (invades fascia prevertebral/carotid/mediastinal vessels))
N (X indetermined, 0 no nodes, 1 regional nodes, 1a level VI, 1b other compartments uni or bilateral)
M (0 or 1) |
| What are stages of TNM classification? | I (any T and N, M0), II (any T and N, M1) if under 55 yrs
I (T1/2, N0,M0), II (T1/2/3, N1, M0), III (T4, anyN M0), IVa (T4b, any N, M0), IVb (any T, any N, M1) |
| What is ATA risk stratification? | Low risk (no metastasis, all tumor resected (R0/R1), no tumor invasion, no aggressive histology - these don't get radioactive iodine)
Intermediate (microscopic invasion of surrounding soft tissues, cervical lymph node metastasis (N1a/b), aggressive histology - these are addressed individually)
High risk (extrathyroid invasion, incomplete resection, distant metastasis - these receive radioactive iodine) |
| What is radioactive iodine ablative therapy? | Aims at ablating remnants of thyroid tissues and potential residual tumor, decreases risk of regional recurrence, facilitates long-term surveillence based on Tg level.
Requires stimulation by TSH by thyroid hormone withdrawal or by administration of recombinant TSH (rhTSH) while pt is on levothyroxine (LT4) therapy.
These recommendations are modulated according to risk factors. |
| What is the algorithm of management of DTC after TT? | . |
| What is levothyroxine therapy? | Aims to replace thyroid hormone, and to suppress growth stimulus of TSH on tumor cells (TSH suppression, targets TSH levels to lower part of normal range in low risk DTC and undetectable TSH (<0.1) in persistent/metastatic disease) |
| How is management of papillary microcarcinoma (T<1cm)? | Constitute 30% of DTCs, usually incidental, long-term survival 100% nearly (mortality 0.3%, distant metastasis 0.4%, local recurrence 2.5%), thyroid lobectomy is recommended. |
| What is medullary thyroid carcinoma MTC? | 5-8% of all thyroid malignancies, 75% of cases occur sporadically, 25% familial (auto dominant mutation in ret proto-oncogene manifests as familial medullary carcinoma (FMC) or MEN2A/B, secretes peptides calcitonin and ACE |
| How is MTC presentation? | Neck mass, pressure symptoms (dysphagia/dysphonia) or w/distant metastasis. Extensive MTC may present w/frequent loose stool and vasomotor flushing resulting from coincident secretion of peptides.
In all cases a family hx should be taken to include first and second degree relatives to search for features of MTC and other endocrinopathies that may occur w/MTC. |
| How is MTC dx? | Basal calcitonin 60-100 pg/ml (pathogneumonic), lower concentrations we may think of other causes (PPI, C-cell hyperplasia, smoking).
If mildly elevated we may use calcitonin stimulation test w/pentagastrin or calcium
Predictive values after stimulation (>250 in women, >500 in men)
Additional investigations preop (24h urine catecholamines rule out pheo, serum Ca exclude hyperpara, Neck CT/MRI if sus of locally advanced disease, germline RET analysis see genetic base, in all pt even w/absent family hx. |
| What is anaplastic thyroid cancer ATC? | Most aggressive tumor and one of the most aggressive tumors in human, more women than men (3:1), peak in 55-65 years, prevalence very low <2% of all thyroid tumors, may be de novo, but in most cases from pre-existing thyroid tumor having undergone additional mutations mainly p53 mutation. |
| How is dx of ATC? | Typical presentation (large, hard, rapid growing mass invading neck causing compressive symptoms (dysphonia, dyspnea, cough, horaseness)
no longer associated w/pT4 stage by defult (could be T3), cases treated w/ resection are staged like other cancers based on tumor size and extension, mean survival is <6 months regardless of tx. |
